Technical Field
The present invention relates generally to the field of electromagnetic shielding materials and coatings. More particularly, the present invention relates to polymer nanocomposites suitable for microwave shielding effectiveness and the economic preparation of such nanocomposites.
Description of the Related Art
The “background” description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description which may not otherwise qualify as prior art at the time of filing, are neither expressly or impliedly admitted as prior art against the present invention.
With the proliferation of more powerful and compact electronic products, electromagnetic interference (EMI) is becoming a significant factor in critical electronic devices. The growth in the application of electronic devices, specifically utilizing microwave frequencies from 300 MHz to 300 GHz, across a broad spectrum of military, industrial, commercial and consumer sectors has created the need for effective shielding materials against EMI. Materials with the capability of absorbing electromagnetic signals are needed in all fields. The EMI shielding of electronic devices and/or radiation sources may be a consideration in the reliable and secure operation of devices, and in preventing possible human health risks.
For efficient shielding action, shielding effectiveness (SE), the material or coating should possess either mobile charge carriers (electrons or holes) or electric and/or magnetic dipoles which interact with the electric (E) and magnetic (H) vectors of the incident EM radiation.
Metals are by far the most common materials for EMI shielding owing to their high electrical conductivity. However, metal shields have the inconvenience of poor mechanical flexibility, exceedingly high weight, propensity to corrosion, and limited tuning of the SE.
Among other alternatives, carbon based materials (graphite, expanded graphite, carbon black, carbon nanotubes and graphene) have also been widely explored for possible application in EMI shielding. However, graphite exhibits poor dispersibility and a high peroclation threshold. Similarly, carbon nanotubes are economically non-viable, difficult to produce at bulk scale and often require purification, auxiliary treatment and fucntionalization steps.
The synthesis of hybrid filler materials based on various combinations of polymers, carbon based materials and/or dielectric/magnetic nanoparticles may be a solution. Polymer nanocomposites represent a novel class of materials that possess a unique combination of electrical, thermal, dielectric, magnetic and/or mechanical properties which are useful for the suppression of electromagnetic noises. The introduction of electrical conductivity to various polymer matrices compensates for the drawbacks of metals and carbon based fillers.
In view of the foregoing, it will be advantageous to provide improvements in EMI shielding structures having nanofillers. In particular, it would be desirable to provide improved EMI shielding structures that may be produced in a relatively lightweight form and at a relatively low cost. It also would be desirable to provide improved methods for producing EMI shielding structures that include nanofillers. Therefore, it would be desirable to improve further the SE as well as mechanical properties of conducting polymer based composites and attain a shielding material that can satisfy relevant techno commercial specifications and maintain process economics at the same time. Disclosed embodiments of the present invention overcome the shortcomings of the prior art as described herein.